This invention relates to a method of controlling a storage system shared by a plurality of computers in a computer system, in particular, a method of allocating a storage device to a computer and starting or stopping the storage device.
Data amount processed by a computer system is remarkably increasing by leaps and bounds while information systems are rapidly advancing owing to deregulation of electronic storage, expansion of Internet businesses, electronification of procedures, etc. In addition to such a dramatic increase in data amount, there have been increasing customers' demands for backup of data stored in a disk device to another disk device (Disk-to-Disk Backup), long-term retention of corporate records of business operations (including transaction information and electronic mail data) for audits, etc. As a result, the data stored in storage systems continues to increase by leaps and bounds, causing the storage systems to become larger in scale. This is followed by attempts to boost the storage systems of corporate information systems on a department/system basis, while it is demanded that management of IT infrastructures, which are becoming more complicate, be more simplified and more efficient. In particular, it is more greatly expected that the management of a storage system be more simplified and the total cost be optimized by utilizing optimal storage systems according to values of data thereof.
JP 2005-011277 A discloses a technique of virtualizing a storage system, as one of methods for reducing management cost of a large-scale storage system. According to the virtualization technique disclosed in JP 2005-011277 A, a first storage system is connected to one or more second storage systems. A device to be provided to an upstream apparatus (for example, a host) by the second storage system (hereinafter, the device will be referred to as “logical device”) is herein provided to the host via the first storage system as a logical device of the first storage system. Hereinafter, such a technique of virtualizing a storage system will be referred to as an external storage system connection method. Upon reception of a request for an input/output with respect to the logical device from a host, the first storage system judges which of a logical device of the second storage system and a physical device such as a disk drive within the first storage system the access target device corresponds to. According to the results, the first storage system transmits an input/output request to a proper access destination.
Further, JP 2003-015915 A discloses a technique of managing a volume whose capacity can be extended dynamically, as one of methods for simplifying design of a storage system. Hereinafter, the volume whose capacity can be extended dynamically will be referred to as an extension volume. According to JP 2003-015915 A, when a logical device is defined, a physical storage area (of a hard disk drive (HDD) or the like) having a device capacity requested by a user is not allocated statistically. On the other hand, a pool area corresponding to a physical storage area is provided within the storage system. When update access is made to the logical device, a physical storage area having a necessary capacity is dynamically added from the pool area only to the portion to be updated. As a result, a large-capacity logical device can be introduced even for the small-capacity physical storage area, which can simplify the storage capacity designing.
Furthermore, JP 2005-157710 A discloses a technique of controlling start/stop of a disk drive, as one of methods for reducing management cost of a large-scale storage system used for long-term retention of mass data. According to JP 2005-157710 A, it is possible to reduce maintenance/management cost (power consumption and apparatus exchange cost) of a storage system by stopping disk rotation of a disk drive (HDD or the like), which corresponds to a logical device designated by a host or backup software, or cutting power supply to the disk drive.